Air pre-cleaners are used on the inlets of air cleaners to prevent coarse or fuzzy solid material, as dust, chaff, snow, lint and other particulate material from entering the air cleaner. If this material, hereinafter referred to as "dirt," is allowed to enter the air cleaner or the carburetor, it will impair the performance of the engine. An air pre-cleaner on the inlet to an air cleaner will reduce the frequency of service of the air cleaner where extreme dirt conditions are encountered. The pre-cleaner is used to separate the majority of the dirt from the incoming air stream thereby increasing the effective dirt collection capacity of the air cleaner.
Air cleaners of the centrifugal type have air deflecting structures which provide the air with a spiral motion to separate the dirt carried in the air. The cleaned air is drawn into the inlet of an engine. Examples of this structure are shown in the following U.S. patents: U.S. Pat. Nos. 451,139; 1,434,562; 1,607,744; 1,917,310; 2,226,045; 2,896,744; 3,382,651; 3,399,515; 3,670,480; 3,740,932; and 3,973,937.